Insulator



Sept. 23, 1930. Q VAN ATTA I 1,776,573

INSULATOR Filed Feb. 17-, 1927 Patented Sept. 23, 1930 UNITED STATES PATENT OFFICE CLOYD IB. VAN ATTA, OF BALTIMORE, MARYLAND, .ASSIGNOR TO LOGKE INSULATOR CORPORATION, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND INSULATOR Application filed February 17, 1927. Serial No. 168,975.

.The invention relates to insulators,-particularly of that type having a pin or its equivalent with a head embedded Within a mass of cementitious material provided for securing purposes.

erally stated, is to provide an insulator of this type with means on the pin, or its equivalent, capable of yielding to permit movement of the pin with respect to the cement as the result of contraction caused by reduction in temperature.

It is wellv known that insulators of the type embodying a metal pin are assembled with the pin in the socket provided therefor,.subsequently to which cementitious material, usually neat Portland cement, is filled into the'socket for embedding the pin. The next step is-generally the sub ection of the assem bled insulator to a steam bath or the like which raises the temperature usually to about 125 F. and this temperature is maintained while the cement sets. When an insulator assembled in this manner is subjected to tem perature changes such as are bound to occur in service, which changes may have a range of, possibly, 100?, with a minimum temperature of possibly more than 125? below that at which the cement is set, there is bound to be considerable relative movement of the parts owing to the differences between the co-eflicients of expansion of porcelain, cement and the metal. The metal Will contract more rapidly and to a greater extent than the cement or porcelain and there is consequently the development of considerable strain at the edge of the head of the pin as the tendency of the pin to contract lengthwise causes, pre- T sumably, an almost straight line outward pressure at the bottom of the socket or recess. A crushing force results which weakens the insulator at this point and when the insulator is subsequently subjected to mechanical strains which are only a fraction of its maximum capacity rupture may occur and this will obviously detract from the eiiiciency. This is only one theory as to the action which occurs andis mentioned merely by way of explanation. Regardless of whether this or some other be the true explanation, the fact does remain that great stress and strain are developed at the edge of the head of the pin, and it is the purpose of the present invention to prov'ide means whereby this objection will be avoided. The principal object of the invention,genf To remedy this defect, it has been proposed to coat the head of the pin with an elastic material, for instance asphaltum, or its equivalent, but this has been found to correct the evil to only a limited extent as the coating is substantially uniform and of insufficient thickness to permit the slippage desirable.

It is with all of the above facts in view that the present invention has for a more specific object the provision-of a cushion of some suitable material applied to the upper edge of the head of the pin at the point where the greatest strain occurs, this cushion being either metallic or nonmetallic, but preferably the former, and being in either event of sufli cient thickness and possessed of, such ductility as to permit the movement of the pin head which results from shrinkage or contraction as the result of a lowered temperature.

Still another object of the invention is to provide a cushion or slippage permitting means of this character which may be applied either in the form of a metallic or other coating or as a distinct and separate element capable of being engaged or mounted upon the pin prior to its insertion within the socket provided for its reception.

An additional object of the invention is to provide means of the character set forth and for the purpose specified which'will not add materially to the cost of production in point of time, labor or material.

To the attainment of the foregoing objects and advantages the invention preferably consists in the construction, arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated Figure 8 is a view similar to Figure 2' showing a slight modification, and v Figure 4 is a similar view showing a still different form.

Referring more particularly to the drawing, the numeral 1 designates the porcelain body of an insulator here disclosed as of that type having an outstanding skirt portion 2 and an upstanding stem 3 upon which is mounted and secured, as by cement l, a cap 5. The porcelain body is shown as having its stem portion provided with a recess 6 for the reception of the pin 7 secured therein by a mass ofcement 8. The pin and cap are illustrated as of the clevis type though naturally there is no limitation in this respect. The pin is here disclosed as of the two-step type, the steps being indicated by the numerals 9 and 10 though it should be distinctly understood that the invention, to be described, is equally well adapted to be applied-to or used in connection with pins having only a single step or having more than two, this detail being of no consequence. It may be Well to reiterate, at thisfpoint in the description, that in insulators of this type, the principal strain comes at the upper end or edge of the step 9.

In carrying out the invention I provide a cushion 11 which is applied to the edge of the pin at the step 9, this cushion being of course interposed between the metal of the pin and the body of cement 8. It is Within the scope of the invention that this cushion be formed as a layer or coating of some yieldable substance and which may be applied in any de-' sired manner whatsoever. However, it is probably preferable that this cushion be formed of ductile metal capable of flowing-or yielding upon the application of considerable strain thereto. Any one of various alloys might be used for the purpose and as there are so many materials that might be suit-able there ,is' no necessity for mentioning any specific one. If this cushion or liner be formed as a coating it would of course be maintained in position upon the pin simply by adhesion and-.it it be of metalit is con 7 ceivable that it could be applied as va coating, forinstance by electrolytic deposition, or it may be made as a ring forced into place and spun or pressed to conform to the curvature at the edge of the pin. as illustrated in Figure 1 and on a larger scale in Figure 2.

It is also conceivable that this liner may be formed from a strip of suitable metal engaged about the pin and crimped into place as disclosed at 12 in Figure 3. Then again, instead of being spun or crimped it may be simply bent around the pin as shown at 13 in Figure 4. Other possibilities will suggest themselves. Ordinarily an insulator of this type has the pin provided with a cushion at its end, which cushion would not in any way interfere with the present invention and which may be in the nature of a coating of asphaltum or the a like indicated at 14 in Figures 1 and 2 or which may be a rubberoid diskor the like as disclosed at 15 in Figure 3.

skirt portion of the insulator or the mouth of the socket as will occur when longitudinal shrinkage or contraction of the pin develops as the result of .a reduction in the temperature to which itis subjected in service as compared with the-temperature at which cement setting is carried out. Clearly, the result of this yieldability is to avoid the bringing of any crushing strains upon the cement at the point indicated and it will he therefore apparent that there will be less likelihood of rupture at this point. An insulator equipped with this liner is consequently bound to be more eflicient and have a greater length of life one of ordinary variety. It is believed that the construction, operation and advantages will be readily apparent to 'one skilled in the. art without further explanation.

While I have; shown and described preferred embodiments of the invention, it should be understood that the disclosure is merely an exemplification of the principles f involved as the right is reserved to make; all such changes in the details of construction as will widen the field of utility and increase the. adaptability of the device provided such changes constitute no departure from the spirit of. the invention or the scope of the claims hereunto appended.

Having thus described the invention, I

claim:

1. In an insulator including a porcelain body having a socket, and a stepped pin with"- in the socket and secured thereto by embed-. ding within a mass of cementitious material, a yieldable cushion surrounding only the edge of the endmost step of the pin at the base of the recess, said cushion being yieldable upon longitudinal contraction of the pin.

2. In an insulator including a dielectric body having a recess therein, and further including a pin cemented within the recess and having a step thereon at the base of the recess, a liner of yieldable material surrounding the pin at only the edge of the step and contacting with the cement.

3. In an insulator including a dielectric body having a recess therein, and further including a pin cemented within the recess and having a step thereon at the base of the recess, a liner of yieldable material surrounding the pin at only the edge of the step and contacting with the cement, said liner-being formed 5 of ductile metal.

4. In a suspension insulator of the cap and pin type, the pin having a step thereon, means carried by the pin and surrounding only the edge of the step for permitting slight rela-' tive movement of the pin with respect to the surrounding mass when the pin contracts under reduction of the temperature thereof subsequent to assembly. 5. In an insulator of the cap and pin type having a recess in which the pin is cemented, the pin having a step thereon at the inner end of the recess, a yieldable metallic liner on the pin at only the edge-of the step and partly covering the side of the step.

6. "In an insulator, the combination of a porcelain body having a stem thereon and formed with a recess within the stem, a cap cemented upon the stem, a pin located within the recess and having a plurality of frustoconical steps thereon, a mass of cement surrounding said steps on the pin and embedding the same within the recess, and a ductile liner upon only the larger end portion or edge of the endmost step nearest the bottom of the recess, said liner acting to reduce stresses and strains exerted by saidendmost step against the cement and transmitted thereby to the porcelain.

In testimony whereof I afiix my signature.

a5 OLOYD B. VAN ATTA. 

